JPH0725161A - Image forming material and method - Google Patents

Abstract

PURPOSE:To obtain an image forming material capable of forming an image of good resolving power and sensitivity by safe and simple dry treatment by providing a photosensitive layer containing a specific cobalt complex and a leuco dye on a support. CONSTITUTION:A specific amt. of a cobalt complex represented by generzal formula (wherein L is a coordination compd. forming a complex along with a cobalt cation, m is an integer of 1-6 and, when m is 2 or more, a plurality of Ls may be same or different, R1-R4 are a group bonded to boron through a carbon atom and n is an integer of 1-3 and, when n is 2 or more, at least one of a plurality of counter anions is a boron anion) and a specific amt. of a leuco dye are dissolved in a solvent along with a binder to prepare a coating soln. for a photosensitive layer. This coating soln. is applied to a support such as a plastic film and dried to form the photosensitive layer to obtain an image forming material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming material and an image forming method, and more particularly to a novel image forming material and an image forming method using a cobalt complex and a leuco dye.

[0002]

2. Description of the Related Art As an image forming method using a leuco dye, a thermosensitive coloring method and a pressure-sensitive coloring method have been widely put into practical use. In these methods, an image is recorded by heat applied from a thermal head or an external pressure such as a pencil, so that the resolution depends on the resolution of a writing device and the resolution is limited.

An attempt to obtain a higher resolution image using a leuco dye is carried out by irradiating a mixture of aromatic amine and polyhalide with light to form an image, and then heating after exposure to unexposed area. There is known a method of subliming and removing the polyhalide of the above for fixing. However, in the fixing method of sublimating the polyhalide, the halide volatilizes in the air and is harmful to the human body, which is not preferable.

In an embodiment in which halogen is not used, there is known a system in which bisimidazole is irradiated with ultraviolet rays to generate radicals to develop a leuco dye, and then an image is fixed with visible light. This method is safe because it does not generate halogen, but has the drawback that sufficient image density cannot be obtained because there is no amplification step.

As another form, US Pat. No. 4,309,255
No. 4,439,280, etc., a method is known in which a color-forming dye is obtained by energizing a water-soluble leuco dye, but this method also has a limit in resolution like the heat-sensitive color-forming method. To be

On the other hand, a method for obtaining an image using a cobalt complex has also been reported. Japanese Unexamined Patent Publication No. 56-126831 discloses an image forming method mainly composed of a photo-oxidizing agent, a color-forming agent that develops color by oxidation, an acid, a cobalt ammine complex, a photo-reducing agent and a hydrogen donor. In this method, instead of reacting the cobalt complex with the color former, a dye is produced from the photooxidant and the color former, and the fixing reaction is carried out using the amine released from the cobalt complex. Is different from. Ammonia generated due to fixing is not preferable in terms of odor.

Further, Japanese Patent Publication No. 54-2091 discloses an image forming method in which a leuco dye and a cobalt complex are combined. In this method, the cobalt complex is reduced in the exposed area and then brought into contact with the leuco dye, whereby an image is formed by a redox reaction between the cobalt complex in the unexposed area and the leuco dye. At this time, since the cobalt complex reduced by exposure is unstable and easily oxidized, fogging is likely to occur and the sensitivity is low.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above problems of the prior art.

That is, a first object of the present invention is to provide an image forming material and an image forming method capable of forming an image having good resolution and sensitivity by a safe and simple dry process. An object is to provide an image forming material and an image forming method capable of forming a stable image. Further, a third object is to provide an image forming material and an image forming method which can be exposed with long wavelength light of 500 nm or more and have high sensitivity.

[0010]

As a result of intensive studies, the present inventors have used a cobalt complex and a leuco dye in the same manner as in the conventional image forming method, but surprisingly, they develop color in the long wavelength exposure region and An image forming material completely different from the image forming method was found.

That is, the above object of the present invention is to provide an image forming material containing a cobalt complex represented by the following general formula (I) and a leuco dye on a support, and an image forming material containing the image forming material. And the image is formed on the exposed portion according to the exposure amount.

[0012]

[Chemical 2]

In the formula, L represents a coordination compound which forms a complex with a cobalt cation. m represents an integer of 1 to 6, and when m is 2 or more, a plurality of Ls may be the same or different.
R ₁ , R ₂ , R ₃ and R ₄ each represent a group bonded to boron through a carbon atom. n represents an integer of 1 to 3, and when n is 2 or more, a plurality of counter anions may be the same or different, but at least one is a boron anion represented by the general formula (I).

The cobalt complex compound represented by the above general formula (I) (hereinafter referred to as the cobalt complex of the present invention) will be described in more detail.

In the cobalt complex, the cobalt cation is a Lewis acid and the coordination compound is a Lewis base, and as the coordination compound represented by L, almost all Lewis bases can be used. From the viewpoint of the stability of the cobalt complex and the reaction activity after reduction, the ligand is preferably a 2- to 3-dentate ligand. Specifically, amines (NH ₃ , ethylenediamine,
Diethylenetriamine, triethylenetetramine, diaminodiacetate, etc.), dipyridine, glyoximine,
Examples include β-diketone and the like, and coordination compounds used in specific examples of cobalt complexes described below and those described on page 3 of JP-A-59-95529.

Radicals R ₁ to which boron is bound via a carbon atom
At least one of R ₄ is preferably an alkyl group or an aralkyl group, particularly preferably R ₁ is an alkyl group or an aralkyl group, and R _{2 to} R ₄ are an aryl group or a heterocyclic group.

The alkyl group represented by R _{1 to} R ₄ includes a linear or branched alkyl group, for example, methyl, ethyl, butyl,
Each group such as i-butyl, hexyl, octyl, stearyl and the like can be mentioned. As the alkenyl group and the alkynyl group, those having 2 to 20 carbon atoms are preferable. The cycloalkyl group is preferably a 5- to 7-membered ring, and the aralkyl group is preferably a benzyl group.

The heterocyclic group is preferably a heterocyclic group having aromaticity, and examples thereof include a thiophene group. The aryl group is preferably a phenyl group or a naphthyl group.

These groups may be further substituted,
As the substituent, a halogen atom, a cyano group, a nitro group, an alkyl group, an aryl group, a hydroxyl group, an amino group (including an alkyl-substituted amino group), an alkoxy group, a carbamoyl group, -COOR ₅ , -OCOR ₅ (R ₅ is And organic groups such as alkyl groups and aryl groups).

Further, at least one of the coordination compounds may contain a dye moiety. The coordination compound containing a dye moiety means that the coordination compound itself is a dye (containing a coordination atom as a part of the constituent of the dye), or a dye having a group capable of coordination as a substituent. Is. In this case, it is possible to spectrally sensitize the dye as a coordination compound so as to be sensitive to visible light to infrared light, or a dye image is formed by a dye or a dye precursor as a coordination compound. It is preferable because it is possible. At least one of the plurality of coordination compounds has a dye moiety, but other coordination compounds may or may not include a dye moiety.

The addition amount of the cobalt complex of the present invention varies depending on the type of cobalt complex and the form of use, but is preferably 0.01 to 5 g per 1 m ^{2 of} the image forming material.

The following compounds may be mentioned as specific examples of the cobalt complex of the present invention. These compounds are synthesized with reference to the method described in JP-A-59-95529.

[0023]

[Chemical 3]

[0024]

[Chemical 4]

[0025]

[Chemical 5]

[0026]

[Chemical 6]

Next, the leuco dye (hereinafter referred to as the leuco dye of the present invention) will be described in detail.

The leuco dye of the present invention is a substantially colorless compound that develops a color upon reaction with a cobalt complex and is stable in an image forming material under ordinary storage conditions. As the leuco dye preferably used,
Starting with a triarylmethane leuco dye represented by crystal violet lactone or a phenothiazine leuco dye represented by benzoyl leuco methylene blue, xanthene, thioxanthene, acridine, phenoxazine, phenazine, diphenylmethane, India Any leuco dyes such as amine-based, fluoran-based, rhodamine-lactam-based, and spiropyran-based leuco dyes may be used as long as they are colored in the manner of the present invention. Among these, triphenylmethane-based and phenothiazine-based leuco dyes represented by the following general formulas (II) and (III) are preferable in terms of good color developability.

[0029]

[Chemical 7]

In the general formulas (II) and (III), X ₁ , X ₂ and X ₃ each represent a group capable of substituting on the benzene ring, and p, q and r each represent an integer of 0 to 5. Represents
p'and q'represent an integer of 0 to 3, respectively. p, q,
When r, p'and q'are 2 or more, a plurality of X ₁ , X ₂ and X ₃ may be the same or different. R ₁₁ and R ₁₂ each represent an alkyl group, and a plurality of R ₁₁ and R ₁₂ may be the same or different.

The group capable of substituting on the benzene ring is preferably an alkyl group, an alkoxy group, an amino group, an alkoxycarbonyl group, an aryl group or a halogen atom.

The addition amount of the leuco dye of the present invention varies depending on the type of leuco dye and the form of use, but per 1 m ^{2 of} the material.
0.1 to 10 g is preferable.

Specific examples of the leuco dye of the present invention include those described in JP-A-56-126831, page 9, line 4 to page 39, line 12, and JP-A-62-94841, page 5. Examples include dyes.

The image-forming material of the present invention basically comprises a support and a photosensitive layer. This photosensitive layer was prepared by dissolving the cobalt complex of the present invention and a leuco dye together with a binder in a solvent or dispersing them in a fine particle form in a solvent to prepare a photosensitive layer coating solution, which was coated on a support. It can be formed by appropriately drying.

The dry thickness of the photosensitive layer is preferably 0.1 to 10 μm.

The binder used is preferably a solvent-soluble polymer such as acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyether sulfone, polyvinyl formal, polyvinyl butyral, polyvinyl acetal, nitrocellulose or ethyl cellulose. These binders are not only used by dissolving one kind or two or more kinds in an organic solvent,
It may be used in the form of latex dispersion.

The amount of the binder used varies depending on whether it has a single-layer structure or a multi-layer structure, depending on the purpose of the image-forming material of the present invention, but is 0.1 to ²⁰ g per 1 m ^{2 of} the support.
Is preferred. The support is not particularly limited as long as it has good dimensional stability and can withstand heating during development, and a transparent plastic film having excellent heat resistance can be used. Specific examples include polymers such as polyethylene terephthalate, polysulfone, polycarbonate, and polyimide. The thickness of this support is usually preferably 10 to 200 μm.

In order to increase the sensitivity of the cobalt complex of the present invention, the photosensitive layer may contain a photoreducing agent or a sensitizer as a photosensitive substance, and examples of these photosensitive substances include naphthoquinone derivatives.

Next, the image forming method of the present invention will be described.

When the image forming material of the present invention is imagewise exposed, an image is formed according to the exposure amount. Further, if the image is exposed to light and subsequently heated (preferably 80 to 200 ° C.), an image having a higher density can be obtained. The image can be fixed on the image-receiving sheet by transferring the color-developed image to the image-receiving sheet or by treating the image-forming material with an acid.

Transfer to the image receiving sheet is carried out by superposing the image receiving sheet and the image forming material and heating (preferably 80 to 200 ° C.). Also, when treating with an acid, fixing by exposing to hydrochloric acid gas for about 1 minute, stacking sheets containing an acid component and heating them, or adding an acid component in another layer and contacting it with heat after exposure. can do.

The acid component may be an inorganic acid or an organic acid, but typical examples thereof include acetic acid, hydrochloric acid and tosylic acid.

The image-forming material of the present invention can be applied to a material capable of recording a full-color image by selecting a leuco dye to be used, or a material for recording a monochrome image.

The image forming material may have a layer such as an intermediate layer, a protective layer and an undercoat layer in addition to the photosensitive layer containing a cobalt complex. Further, in order to record a full-color image, it is preferable that at least three photosensitive layers are spectrally sensitized. Spectral sensitization is achieved by selecting a dye that forms a cobalt complex. In addition, spectral sensitization is made to be sensitive to blue, green, and red light, and a yellow image corresponding to each layer,
A leuco dye may be contained so as to form a magenta image or a cyan image, or may be spectrally sensitized such as green, red, infrared or red, infrared-1, infrared-2.

As the exposure method for the image forming material, sunlight, tungsten light, mercury lamp, halogen lamp, xenon lamp, laser light, light emitting diode, CRT or the like can be used.

[0046]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 The following raw materials were mixed to obtain a photosensitive layer coating liquid according to the present invention.

Cobalt complex (1) 4 g Leuco dye (L-1) 4 g Polyvinyl butyral resin (BL-1: Sekisui Chemical Co., Ltd.) 8 g Methyl ethyl ketone 15 cc Acetone 180 cc Cyclohexanone 5 cc 100 μm thick polyethylene terephthalate base,
The coating solution for photosensitive layer was applied and dried using a wire bar so that the coating amount after drying was 1.4 g / m ² , to prepare an image forming material 1 having a photosensitive layer on a polyethylene terephthalate film. Similarly, image forming materials 2 to 4 having the same constitution were prepared except that the cobalt complex (1) of the image forming material 1 was replaced with a cobalt complex to be described later. Further, the leuco dye (L-1) of the image forming material 1 is added to (L-2), (L-2)
Image forming material 5 having the same configuration except that the image forming material 5 is replaced with
Created 6. Further, the leuco dye (L-
1) was replaced with (L-4), and 0.2 g of 2-i-propoxynaphthoquinone was added to the coating liquid to prepare an image forming material 7.

Further, the comparative image-forming materials 8 and 9 in which the cobalt complex of the image-forming material 1 was replaced with the comparative complexes A and B, and the comparative image-forming materials 10 and 11 in which 0.2 g of 2-i-propoxynaphthoquinone was added to the coating solution were used. It was created. Further, an image forming material 12 having the same constitution was prepared, except that the cobalt complex of the image forming material 1 was replaced with a radical generator (R-1) having an equimolar amount.

Image wedges were overlaid on these image forming materials 1 to 12 and exposed to ultraviolet light. After exposure,
When heated at 130 ° C. for 10 seconds, gradation images of blue for image forming materials 1 to 4 and 7, 5 for magenta, and 6 for yellow could be formed on the exposed portions, respectively.

On the other hand, no image formation was observed in Comparative Materials 8 and 9.

The image forming materials 1 to 4 and 7 to 12 are red light,
5 was green light and 6 was blue light, and the transmission densities of the images were measured.

Separately, the image-forming materials 1 to 11 are placed under a fluorescent lamp.
After storage for a day, the density of the unexposed area was measured and the difference from the initial density of fog was determined (ΔDmin).

The image-forming materials 1 to 7 of the present invention showed almost no change in Dmin, while the comparative materials 10 to 12 showed printout due to the coloring of the leuco dye. The results are also shown below.

[0055]

[0056]

[Chemical 8]

Example 2 The image-forming material 1 of the present invention prepared in Example 1 was exposed to ultraviolet light, exposed to hydrochloric acid gas for 1 minute, and then exposed again to ultraviolet light, but Dmax and Dmin did not change, and an image was obtained. Was found to be fully established.

Example 3 The image forming material 1 of the present invention prepared in Example 1 was UGRA.
It was exposed to ultraviolet light using a plate control wedge (PCW 82) 1982 and heated at 130 ° C for 10 seconds.

The obtained image reproduced a line width of 4 μm and was found to have high resolution.

Example 4 The following raw materials were mixed to obtain a photosensitive layer coating liquid according to the present invention.

Cobalt complex (16) 3 g Leuco dye (L-2) 3 g Polyvinyl butyral resin (BL-1: above) 8 g Methyl ethyl ketone 15 cc Acetone 180 cc Cyclohexanone 5 cc Diethylenetriamine 1 g The same coating solution as in Example 1 was used for the photosensitive layer. An image-forming material 13 according to the present invention was prepared by coating and drying on a polyethylene terephthalate base using a wire bar so that the coating amount after drying was 1.4 g / m ² .

As the image forming material 13, a semiconductor laser (wavelength 82
0 nm) was used for scanning exposure. The exposure energy on the image forming material was 0.5 mJ / cm ² .

After exposure, heating was carried out in the same manner as in Example 1 to obtain a black image corresponding to the exposed area.

Comparative image-forming material 14 was prepared by replacing cobalt complex (16) of image-forming material 13 with comparative cobalt complex (C), and exposure and development were carried out in the same manner as in image-forming material 13 described above. No image formation was observed with the image forming material 14.

[0065]

[Chemical 9]

[0066]

According to the present invention, an image can be formed with high resolution and high sensitivity by a simple dry development process, and by heat treatment and / or acid treatment, the density is higher and the background is free from contamination. A stable image can be formed.

By selecting an appropriate leuco dye, yellow, magenta, and cyan images can be formed, and therefore, full-color images and monochrome images can be used.

Furthermore, it is possible to provide an image forming material which can be written with light having a long wavelength such as a semiconductor laser.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yamato Komamura 1st Sakura-cho, Hino City, Tokyo Konica Stock Company

Claims (9)

[Claims] 1. An image forming material containing a cobalt complex represented by the following general formula (I) and a leuco dye on a support. [Chemical 1] [In the formula, L represents a coordination compound that forms a complex with a cobalt cation. m represents an integer of 1 to 6, and when m is 2 or more, a plurality of Ls may be the same or different. R ₁ ,
R ₂ , R ₃ and R ₄ each represent a group bonded to boron through a carbon atom and may be the same or different. n represents an integer of 1 to 3, and when n is 2 or more, a plurality of counter anions may be the same or different, but at least one is a boron anion represented by the general formula (I). ] 2. The image forming material according to claim 1, wherein in the general formula (I), at least one of L contains a dye or a dye precursor site. 3. The image forming material according to claim 1, wherein in the general formula (I), R _{1 to} R ₄ are an alkyl group, an aryl group, a heterocyclic group or a cyano group. 4. In the general formula (I), at least one of L contains a dye or a dye precursor site, and R
The image forming material according to claim 1, wherein _{1 to} R ₄ are an alkyl group, an aryl group, a heterocyclic group or a cyano group. 5. The image forming material according to claim 1, wherein in the general formula (I), at least one of R _{1 to} R ₄ is an alkyl group. 6. An image forming material containing a cobalt complex represented by the general formula (I) and a leuco dye is imagewise exposed on a support, and an image is formed on an exposed portion according to an exposure amount. A characteristic image forming method. 7. The image forming method according to claim 6, wherein heating is performed after imagewise exposure. 8. The image forming method according to claim 6, further comprising treating with an acid after imagewise exposure. 9. The image forming method according to claim 6, wherein the imagewise exposure is followed by heating and subsequent treatment with an acid.